Selection and constraints in the evolution of sexual dimorphism in ambush bugs

Project Description

Understanding the evolution of complex characters (and whole organisms) is challenging because 1) selection simultaneously acts on many traits and 2) many of these traits are genetically and/or phenotypically correlated. Modern evolutionary biology is equipped with the tools to predict immediate evolutionary change from microevolutionary parameters yet, how processes acting on the micro scale (i.e. within species) translate to patterns at the macro level (i.e. between species) is poorly understood. In particular, little is known regarding the importance of constraints imposed by genetic architecture at long timescales as well as how genetic architecture is, itself, shaped by selection. My research evaluates the relative importance of genetic constraints (estimated from standing trait variance) versus selection (estimated from the wild) for divergence within the genus Phymata, a group that exhibits remarkable diversity in form and colouration.

Additional Scientific Information

The goal is to evaluate the role of sexual selection in determining the trajectory of multivariate phenotypic evolution among geographically distinct populations/species in the genus Phymata. This genus is characterized by prominent sexual dimorphism, suggesting sexual selection playing a major role in diversification. Previous work on one species of this group further implicates sexual selection as potentially powerful agent for the evolution of some aspects of colour dimorphism in Phymata. On the other hand, the group shows considerable phenotypic conservatism for other colour pattern traits. Theoretically, this could reflect genetic constraints in the form of genetic correlations among traits (and across sexes) that persist for long periods, strongly restricting the degree of divergence. Alternatively, this conservatism could be! the result of ecological demands that are shared among species (i.e. stable “adaptive zones” or niche conservatism). Current work focuses on testing these alternative explanations for multivariate sexual dimorphism in the genus Phymata. Long-term objectives include resolving the phylogenetic relationships among species in this diverse but poorly studied group. New techniques that directly combine such phylogenetic data with microevolutionary parameters (i.e. estimates of selection and genetic variance) will allow for formal tests of the relative roles of ecological and genetic factors in the diversification.

Principal InvestigatorLocke Rowe
Researcher(s)David Punzalan

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